EGR Cleaning

So ive got my roommate's 2012 Prius Three apart to clean the EGR cooler as it was caked with carbon really bad, got it a majority of the way clean but still having issues cleaning the exhaust side of the EGR cooler, ive run brake cleaner, degreaser, pretty much the typical stuff to unclog it and water flows through it but not completely, been racking my brain to try and figure out what else i can do to clean it the rest of the way so i can get this thing back together and running somewhat smoothly, Help

(Photos below are from before cleaning)